split函数的作用是用来分割字符串，通常我们采用的是用什么字符来分割字符串，以达到获取我们想要的字符串，函数的返回值为数组。
常见用法
1.以单个字符分割字符串
string str="abc,def,ghi";
string[] strarr=str.split(',');
foreach(string s in strarr) Response.Write(s.ToString() + "<br>");
2.以字符串分割字符串
string str="abc||def||ghi";
string[] strarr=str.split(new string[] {"||"},StringSplitOptions.None);
foreach(string s in strarr) Response.Write(s.ToString() + "<br>");
StringSplitOptions是一个枚举类型，它表示你分割之后是否需要返回为空的值。
StringSplitOptions.none表示返回空值。
StringSplitOptions.RemoveEmptyEntries表示去除空值。
3.以多个字符分割字符串
string str="abc,def.ghi";
string[] strarr=str.Split(new char[2] {',','.'});
foreach(string s in strarr) Response.Write(s.ToString() + "<br>");
//关于其6个重载方法
public string[] Split(params char[] separator)
public string[] Split(char[] separator, int count)
public string[] Split(char[] separator, StringSplitOptions options)
public string[] Split(string[] separator, StringSplitOptions options)
public string[] Split(char[] separator, int count, StringSplitOptions options)
public string[] Split(string[] separator, int count, StringSplitOptions options)
有的时候我们常常会写成这种错误的写法:str.split(“||”),我们从split几个重载函数中可以看出，没有这种只有一个参数，并且参数是字符串的函数，所以会报错。
6个重载方法的使用
string str="1,2.3,,4";
//1. public string[] Split(params char[] separator)
//基于数组中的字符将字符串拆分为多个子字符串。
string[] split = words.Split(new Char[] { ',' });//返回:{"1","2.3","","4"}
string[] split = words.Split(new Char[] { ',', '.' });//返回:{"1","2","3","","4"}
//2. public string[] Split(char[] separator, int count)
//将字符串分割为指定数目的子字符串
string[] split = words.Split(new Char[] { ',', '.' }, 6);//返回:{"1","2","3","","4"}
//3. public string[] Split(char[] separator, StringSplitOptions options)
string[] split = words.Split(new Char[] { ',', '.' }, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2","3","4"} 不保留空元素
string[] split = words.Split(new Char[] { ',', '.' }, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
//4. public string[] Split(string[] separator, StringSplitOptions options)
string[] split = words.Split(new string[] { ",", "." }, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2","3","4"} 不保留空元素
string[] split = words.Split(new string[] { ",", "." }, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
//5. public string[] Split(char[] separator, int count, StringSplitOptions options)
string[] split = words.Split(new Char[] { ',', '.' }, 2, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2.3,,4"} 不保留空元素
string[] split = words.Split(new Char[] { ',', '.' }, 6, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
//6. public string[] Split(string[] separator, int count, StringSplitOptions options)
string[] split = words.Split(new string[] { ",", "." }, 2, StringSplitOptions.RemoveEmptyEntries);//返回:{"1","2.3,,4"} 不保留空元素
string[] split = words.Split(new string[] { ",", "." }, 6, StringSplitOptions.None);//返回:{"1","2","3","","4"} 保留空元素
参考资料
string.split()方法
https://msdn.microsoft.com/zh-cn/library/system.string.split(v=vs.110
C#中String.Split方法使用详解
http://blog.csdn.net/riyuedangkong1/article/details/52431209